December 06, 2006
Matched to the right loads, an AR15 can be incredibly accurate. Layne is here to give you a few pointers on how to build super-accurate handloads for America's longest-lived battle rifle.
The AR15 and the Ruger 10/22 have something in common other than the fact that both are semiautomatics. Both can be transformed into precision shooting machines by simply upgrading various parts. Hang a match-grade barrel on either rifle and you will likely be rewarded with a noticeable improvement in accuracy. Switch out their triggers and you should be able to shoot them more accurately.
Shoot match-grade ammunition rather than the mart special stuff and group size will likely shrink even more. A big difference between the two rifles is you can handload ammo for the AR15 but you can't for the 10/22, which brings me around to what this report is all about: handloading the .223 for the AR15.
Not too many years ago I spent a bit of my time shooting super-accurate bolt guns chambered to 6mm BR Remington and 6mm PPC in registered benchrest competition, and my averages for five five-shot groups at 100 yards were always well inside half an inch.
I was impressed with the performance of those rifles back then, and I am even more impressed with the accuracy of top-level AR15 rifles being built today. When fed decent ammunition a really good AR will keep five bullets inside half an inch at 100 yards with boring regularity. To me, this is remarkable considering the fact that it was designed for use on the battlefield rather than at the target range.
I mean, a rifle that looks like something out of the pick and shovel section of a hardware store should not be this accurate. But as hundreds of shooters have proven time and again through the years, when top-quality component parts are assembled with great care the AR15 will deliver accuracy once thought possible only with the bolt-action rifle.
The Super Varmint from Les Baer Custom I recently shot is an excellent example of how accurate a really good AR15 can be. But some effort is required on the shooter's part in order for this to happen. For starters, handloads put together haphazardly are good for making noise, but when it comes to ammo for feeding a super-accurate AR you need the best available in order to realize its full accuracy potential.
As odd as it might sound in a report on handloading, shooting factory ammo in a new rifle is a good place to start simply because doing so gives you a baseline for comparing the accuracy of your handloads. This applies more to the .223 Remington than to many other cartridges due not only to the excellent match-grade ammunition available from Federal and Black Hills, but super-accurate varmint loads offered by those two companies as well as Remington, Winchester, and Hornady. Really good match ammo is capable of sub-half-minute-of-angle accuracy, and some of the varmint loads are almost as good.
Choosing The Right Bullets
Next comes the matter of choosing the right bullets for handloads. As a rule, those weighing 40 to 55 grains are the best bets when the .223 is used for varminting and in action rifle competition. Moving up in weight to bullets designed specifically for use on deer-size game we come to the 60-grain Nosler Partition and the 75-grain Swift Scirocco.
Even heavier match-grade bullets, such as the Sierra MatchKing, Berger VLD, and Hornady A-Max, are commonly used for long-range competitive shooting, most commonly out to 600 yards but more and more frequently out to 1000 yards. I also know a few groundhog shooters who shoot the heavy match bullets in quick-twist rifles. Then comes the rifling twist rate issue.
The first M16 rifles built by Colt many years ago had barrels with a rifling twist rate of 1:14 inches. While that was quick enough to stabilize 55-grain bullets at what we consider normal ambient temperatures, bullets became unstable when the mercury plummeted well below 32 degrees Fahrenheit. This prompted the Army to switch to a slightly faster 1:12-inch twist, and then later when the 62-grain SS109/M855 bullet was adopted the specified twist became an even faster 1:7 inches.
The typical factory varmint rifle in .223 Remington has a rifling twist rate of 1:12 inches. This is a good compromise since it is quick enough to stabilize the long 60-grain Nosler Partition and Hornady softnose bullets of the same weight as well as those weighing a tad more, with the 62- and 64-grain bullets from Berger being excellent examples. And yet the 1:12 twist is not too quick to deliver excellent accuracy with various 40-grain bullets.
There are, however, flies waiting around to drop into the handloader's bowl of soup. Through the years I have worked with several 1:12-twist .223s that refused to deliver decent accuracy with any bullet weighing more than 55 grains. The only way to know for certain is to give it a try. If I were to have a rifle rebarreled specifically for use with bullets in the 60- to 64-grain weight range I would hedge my bet by specifying a 1:10 twist. Then there would be no question of stability with those bullets, and the barrel should still deliver acceptable accuracy with bullets as light as 50 grains and probably those weighing 40 grains as well.
Match rifles in .223 Remington, the AR15 in particular, are available with barrels in a variety of rifling twist rates. Making proper choices among the various bullet weights boils down to a simple matter of how slow or quick the rifling pitch is. As a rule, optimum twist rate for bullets weighing 40 to 55 grains is 1:12 inches--although as previously mentioned, some rifles with that twist rate will handle some bullets as heavy as 64 grains.
Moving on up in weight (and more importantly, in length) the Sierra 69-grain MatchKing requires no less than a 1:10-inch twist while 1:8-inch is the slowest twist that will stabilize the 77- and 80-grain MatchKings and the 75-grain Swift Scirocco. The incredibly long 90-grain MatchKing and the even longer 90-grain VLD (Very Low Drag) from Berger require a 1:7-inch twist, and some long-distance competitors are shooting them in barrels as quick as 1:6 and 1:6.5 inches. The rifling twist rules-of-thumb I have mentioned also apply to other bullets of similar lengths available from not only Sierra and Berger but from Hornady and other makers as well.
I have yet to work with a barrel with a rifling twist rate quicker than 1:8 inches, but those who have tell me that while the occasional rifle will shoot 80-grain bullets quite accurately, most rifles prefer 90-grain bullets only and will seldom deliver acceptable accuracy with anything lighter. A twist rate of 1:8 inches is the best compromise for those who wish to shoot reasonably light and reasonably heavy bullets in the .223 Remington, and it is what I prefer for all-around use.
Some bullets weighing less than 50 grains will absolutely not work here simply because the centrifugal force tears their thin jackets apart in flight before they reach the target. This is of no consequence to me since I prefer 50- and 55-grain bullets when shooting varmints with this cartridge. On the opposite end of the bullet weight range, the 1:8 twist is just about perfect for the long 80-grain Sierra and Berger match bullets that many competitors have proven to be entirely adequate for shooting out to 600 yards--a few more are using them successfully at 1000 yards. That's as far away as I intend to shoot at anything with any rifle in .223 Remington. In other words, if it can't be done with the 80-grain bullet, I probably won't try doing it with one weighing 90 grains.
When choosing bullets to shoot from your AR15 don't overlook the fact that the extremely heavy-for-caliber bullets are intended for single-shot loading only and they were designed to be seated out to a greater overall length than the magazine box will handle. Maximum overall cartridge length for the magazine is around 2.275 inches, and with some of the heavyweights seated to that length, part of the case neck is out over the ogive of the bullet rather than over its shank with the result inadequate case neck tension on the bullet. On top of that, they would extend quite deeply into the case and use up a lot of what is already a fairly small powder space. As a rule, the Sierra 77-grain MatchKing and Berger 73-grain VLD are the longest bullets that should be seated deeply enough to feed from the magazine. All the others should be seated out of the case for single-shot loading.
Selecting Optimum Propellants
Some of the powders that have proven to be ideal for use in the .223 with bullets in the light to medium weight ranges are a bit quick in burn rate for the heavyweights. For example, Reloder 7 is an excellent choice for bullets weighing anywhere from 40 to 55 grains, but the slower burning Reloder 15 is a better choice for those weighing 60 grains and up. The same applies to other brands of propellants. For 40-grain bullets Sierra recommends powders such as VihtaVuori N-130, IMR-4198, and Hodgdon H322 whereas slower burning powders such as VV N-550, IMR-4064, and H4895 are recommended for the 90-grain MatchKing.
Using The Right Primers & Cases
Regardless of bullet weight, most of the powders suitable for use in the .223 are ignited quite uniformly by standard-force primers. I am partial to the Federal Gold Medal 205M; the Winchester WSR is quite popular among those who shoot the AR15 in Service Rifle competition.
Any good brand of case will do for target practice and varmint shooting, but Winchester brass is probably the most popular among competitors due to its hardness and excellent weight uniformity. For trouble-free chambering in the AR15, cases should be full-length resized rather than neck sized. Top-quality, out-of-box components properly assembled on any good single-stage or progressive reloader will produce ammunition capable of half-minute-of-angle or better and that's good enough to satisfy most of us. I am sure it is also far better than the original designer of the M16/AR15 rifle ever dreamed of achieving with what went on to become America's longest-lived battle rifle.
ONE SUPER ACCURATE RIFLE
The test rifle I used when shooting various handloads for this report was a Super Varmint from Les Baer Custom, and it was not the first one I have worked with. Several years ago I shot the same rifle with a 1:12 twist, and it consistently delivered five-shot groups of less than an inch at 100 yards with both handloads and factory ammo.
The rifle I shot more recently was basically the same except for the quicker 1:8-inch twist rate of its barrel. With LBC precision EDM scope mounting rings holding a brilliantly clear Weaver 6-20X Grand Slam scope atop its flattop receiver, it weighed two ounces beyond 12 pounds on my postal scale, and that along with its incredible accuracy potential made shooting tiny little groups falling-off-a-log easy. The group I am most proud of was fired with the Sierra 77-grain MatchKing seated atop 24.0 grains of Reloder 15. I wanted to shoot that load through the magazine so I used the Sierra-recommended cartridge overall length of 2.260 inches. Fired from a benchrest at 600 yards on a windless day, the group is a 10-shooter and it measures an incredible 2.842 inches (or roughly 0.474 minute-of-angle). Can I repeat that performance on demand? Probably not. Is the rifle capable of doing it all the time? Most definitely.
One of the reasons I was able to shoot the Super Varmint so accurately is its trigger. Of two-stage design, it is from Jewell; the trigger finger first takes up the initial stage with 34 ounces of pull and then suddenly at the 42-ounce mark it breaks cleanly. AR triggers don't get any better than this. The barrel is benchrest-grade 416R stainless, and its size accounts for a good bit of the overall weight. The 24-inch barrel has a muzzle diameter of .925 inch. The Super Varmint is also available with 18- and 22-inch tubes, and rifling twist rate options are 1:7, 1:8, 1:9, and 1:12 inches. Upper and lower receivers are precision-machined from forgings, and the former is available with or without forward assist. These and all other parts, such as the chromed bolt and carrier, extractor, aluminum gas block with Picatinny top rail, and the free-floating tubular handguard, are manufactured in house by LBC. Accessories included in the package are quick-detach Versa Pod, 20-round magazine, padded rifle case (with side pockets big enough to hold lots of stuff). Like several other AR15 variants offered by LBC, the Super Varmint comes with a half-minute-of-angle guarantee. Believe me when I say it is no brag.